Autofitting your selection is an extremely useful piece of functionality.

Lets say that you have a large piece of text in the first row, but then very small text in subsequent rows.

You can save valuable screen real estate by autofitting the selection.

Here's how much screen space you use when you autofit the column:

Now, select everything apart from the first cell... then press in sequence:
"ALT" then "O" then "C" then "A"
Now look how much less screen space you use when you autofit the selection:

Training Video on how to Autofit your Selection: